Survey of Energy Resources 2007
Geothermal Country Notes
United States of America
The USA possesses a huge geothermal resource, estimated at some
50 000 MWe, located largely in the western half of the country. Research has shown that geothermal energy has been used in North America for many thousands of years but the first documented commercial use was in 1830 in Arkansas. In 1922 an experimental plant began generating electricity in California but, proving to be uneconomic, it soon fell into disuse. Another 38 years were to pass before the first large-scale power plant began operations at The Geysers, north of San Francisco, California. The USA is the world's largest producer of electricity generated from geothermal energy.
Only California, Nevada, Hawaii and Utah utilise geothermal energy for power generation; investigative studies undertaken in Oregon during the early 1990s proved to be unsuccessful. However, the 1990s saw dramatic change in the geothermal power industry: plants came on line, plants were retired, there were changes of ownership (resulting, in some cases, in operational efficiencies), etc. By end-2005 total effective capacity stood at 2 564 MWe. It is reported that 88 MWe of capacity is under construction and planned projects would add 213 MWe capacity.
Geothermal heat suitable for direct utilisation is far more widespread through the US, ranging from New York State in the east to Alaska in the west. At end-2004, a total of 617 MWt installed capacity was used for fish and animal farming (138 MWt), greenhouse heating (97 MWt), bathing and swimming (112 MWt), district heating (84 MWt), space heating (146 MWt), agricultural drying (36 MWt), industrial process heat (2 MWt), and snow melting (2 MWt).
In addition, it is estimated that between 600 000 and 800 000 heat pumps are installed in the US (in all 50 states but more commonly in the mid-west, mid-Atlantic and southern states).
The US Department of Energy continues to support geothermal energy through sharing the cost of R&D with industry, funding state programmes and providing technical assistance to small developers (through GeoPowering the West Program).